Semi-weekly south Kentuckian. [volume] (Hopkinsville, Ky.) 1883-1889, 1887-10-11
GATHERING THE GOLD.
Methods Adopted for Getting the Meti
Out Of the Free Milling Ore.

Methods Adopted for Getting the Metal
Out OF the Free Milling Ore.
At Breckenridge, Col. the other day.
] saw the Jumbo stamp-mill and there
got fair insight into the method of
getting the gold out of what is called
free milling ore. The stuff that comes
from the mine is first put through a
crusher, which breaks it up fine, and
the product is then run through rollers
which pulverizes it, though, perhaps,
coarsely. From the rollers it falls to
the lower noor, upon which the NOR
tars are located. At the Jumbo mill
the dirt is fed to the stamps by hand;
In other mills it falls through chutes
which work automatically, and never
feed more than is necessary at a
time, The stamps are arranged in
batteries of five stamps each. They
work up and down in oak easements,
and their motions are regulated by
cams on shaft geared to the motive
machinery. The stamps weigh from
450 to 900 pounds, according to the
character of the ore treated. Water
flows into the mortars and out of them
down tables to tho waste fumes which
carry the refuse away. Stamps in this
country run rs low as thirty drops a
minute, and seldom over sixty; in
California they drop seventy to 100
times minute. The two kinds of mills
are distinguished by the rapidity or
slowness of their drops, and those used
here are all built by Peter Mcfarland,
and are called Gilpin County mills,
from McFarland's home place, which
Is in Gilpin County, while the others
are known as California mills. They
cost from $3.50 for a fiye-stamp pros
pecting mill to $4,000 for l00-stamp
mill. The dirtbeing fed into the mortars
is pounded and pounded by the stamps;
the silica, porphyry and other refuse
is carried off by the water, but the gold
is caught by two copper plates coated
with quicksilver that line the sides of
the mortar; any Of the precious metal
that escapes from the mortar may be
caught on the 4x8 feet copper plates
that are quicksilver coated and lie on
the table over which the refuse is car
ried. Some OF the gold gets away, OF
course, but the Jumbo saves as much
as 80 per cent. of its gold, and McFar-
land is now building mills which he
claims will save 95 per cent. Of the as
sayed value of ore. tt atr
Concentrators are used where the ore
is too low grade to pay for smelling in
its crude state. BY concentrating a $40
OF S12 ore may be handled so that the
mill product, which will represent six
or seven tons in ore, may be worth $40
to $50 per ton. The scheme is very
simple. The crushed and rolled ore is
fed through chutes to revolving screens
ranging in size from three-fourths inch
openings to one-eighth. Each Of these
screens has a trough and chute which
feeds a jig box. The jig boxes work on
an eccentric and keep up a spasm-like
motion. THERE'S screen in each about
six inches fromthe top, and this screen
is covered with lead or other heavy
ore material, which prevents the
silica, porphyry and other light stuff
from going through, The motion
shakes the metal to the bottom OF the
boxes, where 1t remains until valves in
the bottom are opened and the concen-